Polyimide is a highly useful polymer material which is excellent in heat resistance, forming property, and mechanical and electric properties, and many types of polyimides have been heretofore developed and widely used in various industrial fields.
Polyimide having aforementioned properties has been used in combination with an inorganic material in many cases. For example, a composite material combining polyimide having an insulation function and a conductive metal has been used as an electronic material. In particular, a metal-coated polyimide material produced by compositing a polyimide film and a metal foil is useful, and has been used for a flexible printed circuit board (FPC) or a board for tape automated bonding (TAB) or the like.
As a method for producing such a metal-coated polyimide material, various methods have been known up to now. For one thing, a method for subjecting polyimide to electroless plating or electroplating has been known. That is, it is a method for forming a metal layer on a surface of the polyimide film by subjecting the polyimide film to electroless plating and subsequently, as necessary, subjecting it to electroplating.
Patent Document 1 discloses an electroless plating method characterized in that a material to be plated is pre-treated with a solution containing alkali metal salts, and then treated with a compound including a silane coupling agent with a substituent having a metal capturing capability in the molecule as an effective ingredient, and subsequently treated with an aqueous solution of a noble metal compound for capturing the noble metal by a silane coupling agent, and then the material to be plated is subjected to electroless plating.
Patent Document 2 discloses a method of preparing a metal-plated film for forming a conductive circuit pattern on the surface of the polyimide substrate characterized in that the surface of the polyimide substrate is treated with a solution containing an organic disulfide compound having a primary amino group or an organic thiol compound having a primary amino group in the presence of an alkaline substance in advance.
In Non-Patent Document 1, there has been reviewed a method for coating the surface of the straight chain polyimide film with a polymer compound having a pyridyl group having a metal coordination capacity in the main chain.
Patent Document 1: Japanese Laid-open Patent Publication No. 2002-226972
Patent Document 2: Japanese Laid-open Patent Publication No. 2002-208768
Non-Patent Document 1: Macromol. Mater. Eng. Vol. 288, pp. 152-163 (2003)